Supplement: Light-Responsive Ruthenium Compounds for Applications in Disease

This proposal seeks to develop a new class of light-responsive inorganic materials as chemotherapeutic agents. Cisplatin and its analogues remain the standard therapy for a variety of cancers, despite their nonspecific mechanism of action with nucleic acids, resulting in general cytotoxicity and debilitating side-effects. A promising approach that will provide several key advantages is to combine the reactivity of metal-based drugs with the selectivity of photodynamic therapy (PDT) to increase the targeting of malignant tissues and reducing side-effects. We have shown that structural distortion can be utilized to promote photochemical reactions to create reactive ruthenium species that are strongly electrophilic and highly photo-toxic in cell based assays. This distortion can be used to control light-activated cytotoxicity for the creation of selective and potent chemotherapeutics. A new class of ruthenium-based compounds is under development that have a readily modifiable modular design to facilitate rapidly incorporation of key molecular components to efficiently develop materials exhibiting selectivity and controlled reactivity. Coordination chemistry will be used to generate a structurally diverse family of three-dimensional chiral ruthenium compounds in a self-assembled manner. The structural variations in the materials will be correlated to cytotoxic efficacy using high-throughput cell survival assays, and the most promising compounds will be assessed for Pharmacokinetic (PK) properties, Maximum Tolerated Dose (MTD) and efficacy in mouse xenograft models of lung cancer and melanoma. Mechanism of action studies will be used to define the currently unknown process of cell killing. In support of this aim, a novel chemical labeling strategy is under development to facilitate imaging of the subcellular and potentially sub-organellar localization of active compounds using both Light and Electron Microscopy. This approach could be extended to additional imaging applications in tissues. Alternative approaches utilize biotin-labeled ruthenium materials for target pull-down, with cellular targets identified through a process of gel electrophoresis, chromatography, and mass spectrometry. Cisplatin, the benchmark inorganic chemotherapeutic, will be used for comparison in all mechanism of action studies. The goal is to identify the structural features that cause ruthenium materials to utilize the same biological target(s) as cisplatin, and how they may be directed to different functional targets via structural modification. Upon completion of these studies, we will have expanded our knowledge of the fundamental photochemistry of ruthenium complexes, developed potent and selective cytotoxic chemical entities, identified their mechanism of action, and developed a new tool for the imaging of small molecules in biological systems